Arrangement for the quantitative and qualitative analysis of particles in gases

ABSTRACT

An arrangement is described for the quantitative and qualitative analysis of particles in gases, especially of particles in the exhaust gas of internal combustion engines, comprising a vibrating system with at least one vibration sensor, preferably a piezoelectric resonator, which is provided with at least one collecting surface for the particles to be analyzed, a circuit for the determination of characteristic vibration parameters as well as guide and transport arrangements for the gas to be analyzed. In order to obtain as large as possible a measuring range with a linear characteristic line and therewith a great sensitivity and dynamics with respect to the mass load in the entire measuring range, there is provided a vibration sensor stationary relative to the measuring chamber, and at least one active deflecting device for the gas or the particles contained in the gas.

BACKGROUND OF THE INVENTION

[0001] The invention relates to an arrangement for the quantitative andqualitative analysis of particles in gases, especially of particles inthe exhaust gas of internal combustion engines, comprising a vibratingsystem with at least one vibration sensor, preferably a piezoelectricresonator, which is provided with at least one active collecting surfacefor the particles to be analyzed, which, through at least one outletopening, enter the measuring chamber containing the vibration sensor, acircuit for determining characteristic vibration parameters, as well asguide and transport arrangements for the gas to be analyzed; as well asa process for the quantitative and qualitative analysis of particles ingases, especially of particles in the exhaust gas of internal combustionengines, in which the particles are precipitated through at least oneoutlet opening onto at least one active collecting surface of at leastone stationary vibration sensor, preferably a piezoelectric resonator,of a vibration system, and by the particle precipitation there isdetermined the change of characteristic vibration parameters.

[0002] The measuring of particle emissions which arise in the combustionprocess of organic material has been of great interest for many years.The influence on human health of particles that are present in thebreathing air stands at present at the center of many scientificinvestigations. Since the particles can be conceived as the measure ofan incomplete combustion process, it is possible to raise the efficiencyonly by a continuous optimization of the combustion process. andtherewith to reduce the particle emission. From this continuousoptimization there results high demands on the particle measuring systemwith regard to resolution, measuring range and dynamics. With vibrationsensors, such as piezoelectric resonators for example, it is possible todetermine the foreign mass applied directly to the sensor surface bymeans of the thereby occurring frequency change. In order to be able tomeasure the particle mass and/or the concentration of particles, withthe aid of a probe, a certain volume of air is drawn through a particlecollector. This measurement can be executed in one stage, so that ifpossible all the particles in the air stream are precipitated on aresonator, or in several stages, in which case here advantageouslyparticles in defined size classes are precipitated on severalresonators, wherewith not only the mass is determinable, but also aclassification according to particle size is possible. The precipitationcan occur, for example, by electrostatic processes, i.e., accelerationof the particles in the electric field onto the oscillating crystal, asis described, in U.S. Pat. No. 5,892,141.

[0003] The precipitation characteristic on the resonator collectingsurface is given, in the case of gas samples fed-in through an opening,such as a nozzle or the like, directly over the resonator surface (anexample for this is given in document U.S. Pat. No. 3,561,253), inaddition to the flow-through, by the particle size, the geometry of theopening and its distance from the surface of the resonator. Even withseveral openings per resonator surface, as is disclosed in U.S. Pat. No.4,446,720, after an initially linear decrease of the frequency, withrising particle load of the resonator, the frequency change above about100 Hz begins to follow an exponential course.

[0004] In the article “Applications of Piezoelectric Quartz CrystalMicrobalances” in “Methods and Phenomena, Their Applications in Scienceand Technology”, vol. 7, Elsevier 1984, an arrangement is described inwhich the vibration crystal is moved horizontally under a precipitationnozzle by means of a motor, in order to achieve a more uniformdistribution of the particles. In such an arrangement, a relatively longperiod of time of several seconds is required until several layers ofparticles are precipitated, or the vibrating crystal must be moved backand forth very rapidly, for which purpose the arrangement must be builtvery stable and massive, and therewith correspondingly complicated andill-suited for mobile use.

[0005] Also, from further documents on the state of the art, such asU.S. Pat. No. 5,056,355, no guiding arrangement for the gas stream is tobe derived with which a control of the gas stream and therewith also ofthe particle stream would be possible to implement.

[0006] Likewise with the gas detector of DE 31 06 385, no arrangement ispresent which makes possible such a control of the impact zone of theparticles over the collecting surface of the vibration sensor. On thecontrary, it is a matter in this reference of a passive deflectingarrangement which does, to be sure, deflect the gas stream so that thelatter will definitely pass onto the vibration sensor, but which then,however, permits no further influencing or control of the gas stream.

SUMMARY OF THE INVENTION

[0007] The problem of the present invention, therefore, is anarrangement and a process for the analysis of particles in gases, whichwith avoidance of the disadvantages of the state of the art, offers witha very simple and easy construction, as great as possible a measuringzone with a linear characteristic curve and therewith a greatsensitivity and dynamics with respect to the mass loading in the entiremeasuring zone.

[0008] For the solution of this problem, the inventive arrangementdescribed at the outset is characterized in that there are providedvibration sensors stationary with respect to the measuring chamber, andat least one active guiding and steering device for the gas or theparticles contained therein. Therewith, despite a simple and easyconstruction, there can be achieved a uniform distribution of theprecipitated particles over the active collecting surface of thevibration sensor, and therewith the desired wide measuring range with alinear characteristic curve and a high sensitivity and dynamics. Throughthe movement of the impact zone of the particles over the activecollecting surface of the vibration sensor, the linear range of thefrequency change by particle load can be significantly extended, sincethe saturation of individual zones can be avoided or at least be drawnout much longer than with conventional systems.

[0009] A first, structurally very simple and dependable form ofexecution of the arrangement according to the invention is characterizedin that as an active guiding and controlling device there is provided ashutter with at least one shutter opening, the transversable crosssection area of which is small as compared to the active collectingsurface of the vibration sensor, in combination with an arrangement thatmoves the shutter relative to the active collecting surface of thevibration sensor, in which arrangement the movement runs essentiallyparallel to the active collecting surface of the vibration sensor.

[0010] According to a further feature of the invention an arrangement isprovided for the movement of the shutter, which moves at least oneshutter opening on a closed path. Therewith, with as little as possiblestructure height, there can be achieved a uniform precipitation over alarge surface area of the active vibration sensor surface.

[0011] In order to obtain a simply built arrangement, which is alsoattuned to the typically circular active collecting surfaces of thevibration sensors, there is provided an arrangement for the movement ofthe, which moves at least one of the shutter openings over anessentially circular path, in which the axis of the circular movement isnormally oriented essentially perpendicular to the active collectingsurface.

[0012] Altogether it is provided there that the vibration sensor, and/orits active collecting surface, is advantageously constructedrotationally symmetrical about the axis of the circular movement,whereby there is achieved an optimal utilization of the collectingsurface.

[0013] If, according to a further feature of the invention, anarrangement for moving the shutter is provided, which moves at least oneshutter opening along a path that arises through the superposing of atleast two rotary movements with essentially parallel axes of rotation,which axes of rotation are oriented essentially perpendicular to theactive collecting surface, there can be achieved a still better and alsomore uniform surface coverage for the precipitation onto the activecollecting surface of the vibration sensor, and that in a relativelyshort time.

[0014] According to a further feature of the invention, it is providedthat an arrangement for the movement of the blind relative to thevibration sensor is provided with an alternating speed, or with analternating angular velocity.

[0015] For devices with electrostatic precipitation, the corona needle,present in any case, can be coupled according to the invention witharrangements for its movement relative to the vibration sensor, so thatby reason or these movements, the electric field is continuously varied,and in this manner brings about the desired alteration of the impactzone of the particles on the vibration sensor. In this form ofexecution, additional components for the deflection of the gas jet or ofthe particles are avoided insofar as possible, whereby a lightarrangement results, with which also the susceptibility tomalfunctioning and the maintenance expenditure are again reduced.

[0016] According to a further form of execution of the invention, thearrangement can also be characterized in that as an active guiding andsteering device, there is provided at least one arrangement for thegeneration of a variable electrical magnetic or electromagnetic fieldbetween the outlet opening and the vibration sensor, as well as anarrangement for the electrical charging of the particles in the gas. Inorder to obtain a defined deflection or altogether a deflection of theparticles also for normally neutral particles, the particles should beelectrically charged before reaching the outlet opening. This charge canoccur mono-polarly or bi-polarly by a corona discharge or a radioactivesource. With this form of execution, movable parts can be avoided to thegreatest possible extent and therewith the weight of the apparatus, thesusceptibility to malfunctioning and the expenditure for itsmaintenance, can be significantly reduced. Further, in a simple mannerand without complicated mechanical intervention, the path of theparticle beam can be altered or adapted.

[0017] According to a further form of execution of the invention thereis provided as an active guide and steering device, at least one outletopening for an additional gas jet, preferably to the side of the openingfor the entry of the particles, in which case the axes of the outletopenings preferably enclose between them an angle not equal to zero, orthere can also be provided an active guide and steering device for thegeneration of an alternating current speed and/or direction. A furtherform of execution is presented by an arrangement in which the devicesfor the generation of alternating gas or of particle speeds are providedin the entry opening.

[0018] The process for particle analysis in gases described at theoutset is characterized, according to the invention, in that during themeasuring period, the particle jet is moved actively over anever-alternating zone the collecting surface of the vibration sensor.Thereby, a local saturation of the active collecting surface of thevibration sensor is avoided, the particles are distributed moreuniformly on the active collecting surface and from this there results asubstantial widening of the linear constituent of the measuring range,with higher sensitivity and dynamics with respect to the mass load overthe entire measuring range.

[0019] Advantageously there, according to a further feature of theinvention, it is provided that the particle jet is led along a closedcurve, whereby a very uniform precipitation over a large surface area ofthe active collecting surface of the vibration sensor can be achievedwith as small as possible a construction height if, according to afurther feature of the invention, over the time interval of themeasurement, an ever-alternating zone of the active collecting surfaceof the vibration sensor is excepted from the shielding, which zonedefines a closed curve.

[0020] An especially simple variant there, which also takes intoconsideration the typical form of the active collecting surfaces of thevibration sensors, is characterized in that the particle jet is ledalong a circular path.

[0021] According to another development of the inventive process, theparticle jet is led along a curve which arises by the superposing of atleast two rotary movements with axes of rotation perpendicular to theactive collecting surfaces. With this development there can be achieveda still better and also more uniform surface coverage for theprecipitation of the particles on the active collecting surface of thevibration sensor, and that in a relatively short time.

[0022] Advantageously it is provided in all these variants that theparticle jet is guided with an alternating speed, or with an alternatingannular velocity.

[0023] In a variant embodiment of the invention with electrostaticprecipitation, the electric field used for ionization of the particlescan be continuously altered, so that therewith there occurs a change ofthe impact zone of the particle jet on the active collecting surface ofthe vibration sensor.

[0024] According to a fir form of execution of the inventive process,there is provided, additionally to or alternatively to theabove-described features, that the particle jet is deflected by analternating electrical, magnetic or electromagnetic field and led overthe active collecting surface of the vibration sensor.

[0025] According to a further feature of the invention, it can also beprovided that a gas jet of alternating flow speed and/or direction isdirected onto the particle jet, and that the latter is therewithdeflected.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In the following description some preferred examples of executionare to be explained in detail with reference to the drawing.

[0027]FIG. 1 shows a schematic representation of a device according tothe invention in side view.

[0028]FIG. 2 is a schematic representation in plan view of a shutter foran arrangement according to the invention.

[0029]FIG. 3a shows the precipitation pattern of the shutter of FIG. 2in a stationary application.

[0030]FIG. 3b shows the precipitation pattern with rotation of theshutter of FIG. 2 about its central axis.

[0031]FIG. 4 shows a schematic representation of a shutter arrangementwith superposition of two rotary movements.

[0032]FIG. 5 shows a plan view of an alternate embodiment of a shutteraccording to the invention.

[0033]FIG. 6 is a time-frequency diagram with comparison of conventionalarrangements with the arrangement according to the invention.

[0034]FIG. 7 shows a schematic view of an embodiment with electricaldeflection.

[0035]FIG. 8 shows a schematic view of an embodiment with magneticdeflection.

[0036]FIG. 9 shows a schematic view of an embodiment with electrical andmagnetic deflection.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] Over conventional and not-represented sample-taking devicescontaining usual-type conducting and transport arrangements, suctionpumps and the like for the gas laden with the particles 1 to beanalyzed, this gas is brought into a chamber in which a vibrating systemis present, in which, by the mass loading of a sensitive collectingsurface of a vibration sensor 2, there comes about a change of theacoustic parameters of the vibration sensor 2. Pulsed or also continuousvibration excitation can be used. The parameters of the collectingsurfaces comprise, for example, the thickness, the surface mass density,the mechanical impedance on the surface or the speed of sound in thezone of the surface, whereby according to the type of vibrating system,i.e., volume or surface vibrating systems, there result changes of theresonance frequency or of the appertaining period duration, of therunning time of the sound pulse or the like. These changes are detectedon the electro-acoustic converter of the vibrating system and then drawnupon in a manner known per se for the determination of the mass loading.One of the typically used vibrating systems contains a piezoelectricresonator with a piezoelectric vibration sensor 2. The piezoelectricresonator is further provided, inter alia, with an oscillator circuit 3and a switching arrangement 4, for the control of the oscillator circuit3 as well as for the recording, storing, and displaying of themeasurement data.

[0038] On the piezoelectric vibration sensor 2 there is mounted acollecting electrode 5 as an active collecting surface for the particles1 to be analyzed and, on the side of the resonator 2 lying opposite thecollecting electrode 5 there is mounted a counter-electrode 6. Thecollecting electrode 5 is constructed preferably as an open-poredstructure with pores, in which pores there are captured the particlesthat are collected by electrostatic precipitation or by impaction on thepiezoelectric resonator 2, wherein advantageously the size of the poresof the collecting electrode 5 is adapted to the size to be expected ofthe particles to be measured.

[0039] Obviously the collecting electrode 5, and this holds also for thecounter-electrode 6, does not have to be provided directly on the activesection of the piezoelectric vibration sensor 2, but could also bemounted on a non-piezo-electrically active extension, preferably with anoptimal effect on the change of the resonance frequency on the sidelying opposite the clamp of the sensor to the oscillator circuit 3.

[0040] The described piezoelectric resonator can be constructed on thebasis of Volume (BAW—Bulk Acoustic Waves) or surface vibration systems(SAW—Surface Acoustic Waves), in which case, through the mass loading ofthe piezoelectric vibration sensor with the particles to be analyzed,there occurs a change of the resonance frequency or of the appertainingperiod duration. For other vibrating systems, in which the running timeof a sound pulse altered in each case according to mass loading ismeasured, surface vibrating systems (SAW) are of primary importance.

[0041] At a short distance above the active collecting surface 5 of thevibration sensor 2 there is arranged at least one shutter 8 as adeflecting device, the shutter includes at least one shutter opening 9which has an outlet opening for the particles 1 a cross section areathat is less than the area of the active collecting surface 5.Preferably the cross section of the shutter opening or openings 9 isvery small with respect to the active collecting surface 5. In eachcase, by reason of the shutter opening 9, the impact zone of theparticles 1 which move in the direction of the arrow A toward thevibration sensor 2, is narrowly limited on the active collecting surface5. The shutter or shutters 8 or their outlet opening 9 is movablerelative to the stationary vibration sensor 2 and therewith in thecourse of the precipitation of the particles 1, is moved over the activecollecting surface 5 of the vibration sensor 2, essentially parallel tothe surface 5, so that the impact zone not shielded by the shutteropening 9 is correspondingly shifted over the active collecting surface5, and therewith the particle jet is led over the active collectingsurface 5 of the vibration sensor 2.

[0042] It is advantageous, as is to be seen in FIG. 2, to provide abovethe active collecting surface 5 of the vibration sensor 2 (notrepresented in FIG. 2) a shutter 8 with several shutter openings 9,which shutter 8 in this case about its central axis, in the zone of thecentral shutter opening 9 a, rotates and this manner, in the course ofthe particle precipitation, it directs the particle jets emerging fromthese shutter openings 9 over different zones of the active collectingsurface 5. The central axis of rotation of the shutter 8 is orientedessentially perpendicular to the active collecting surface 5 of thevibration sensor 2. FIGS. 3a and 3 b show the precipitation patternachievable with the shutter of FIG. 2 on the active collecting surface5, wherein FIG. 3a shows the precipitation pattern with a fixed shutter,as the pattern can also be achieved at best in conventional devices withseveral nozzles for the gas in-feeding. By reason of the larger-surfaceprecipitation by means of the shutter movable according to theinvention, as shown for example, in FIG. 3b, by reason of the clearretardation of saturation effects, there can be achieved an increase ofthe linear zone of the frequency change of the vibration sensor and agreater sensitivity and dynamics over this increased zone.

[0043] Obviously not only circular movements or in general movements ofthe shutter 8 along closed paths are conceivable. Thus, for example,movements of at least one shutter opening 9 are also possible, whichmovements arise through the superposing of at least two movements,preferably rotary movements. An example for such a superposition of tworotary movements is explained in connection with FIG. 4. The shutter 8here with, by way of example, only a single shutter opening 9 rotatesabove the active collecting surface 5 about the central axis of rotationZ oriented perpendicular to the active collecting surface 5. There, thecenter M of the blind 8 moves along the circular path B. Since now theblind 8 itself rotates again about an axis substantially parallel to theaxis Z and passing through its center M in reversed turning direction,symbolized by the arrow D, there is yielded, with corresponding attuningof the angular velocities, a pendulum movement along the line P of theblind opening 9 over the active collecting surface 5 of the vibrationsensor 2. For other relations of angular velocities or like turningdirection of both movements there is yielded, however, a rosetta-typemovement of the blind opening 9 relative to the vibration sensor 2,whereby the particles are precipitated with more surface coverage.

[0044] Another form of execution of a shutter 8 for an arrangementaccording to the invention is represented in FIG. 5. Here the shuttersize is considerably greater than the active collecting surface 5 of thevibration sensor 2, in which of course also several vibration sensors 2and/or active collecting surface zones 5 could be provided in the herecircular movement zone of the shutter openings 9 b. The individual blindopenings 9 b are present in the form of lengthwise slots proceedingradially from the center of the shutter 8, through which there also runsthe axis of rotation oriented essentially perpendicular to the activecollecting surface 5 or to each active collecting surface 5. Bycorresponding guide arrangements it is brought about that always onlythat zone of the shutter 8 is traversed by the particle jet which liesabove an active collecting space zone 5. By reason of the slot-formblind openings 9 b and of their guidance in circular arcs over theactive collecting surface 5 by reason of the described geometry, theparticles 1 are precipitated on the active collecting surface 5 instrips with a width which corresponds to the length of the slot-formblind openings 9 b, and in a number of layers which corresponds to thenumber of slot run-throughs during the measurement duration.

[0045] The time-frequency diagram of FIG. 6 explains the advantages andeffects of the arrangement according to the invention. There the leftcurve corresponds to a measurement with a stationary shutter 8 as it isrepresented in FIG. 2, and the precipitation pattern of whichcorresponds to that of FIG. 3a. After a brief measuring time, thefrequency caused by the increasing mass loading of the active collectingsurface of the vibration sensors changes from a linear course to anexponential course with still only the slightest frequency change onfurther mass loading. In contrast to this, the right curve of FIG. 6,which has been determined by a measurement with a shutter of FIG. 2,rotated about its axis, shows that through the rotation and therewiththe distribution of the precipitated particles in correspondence to apattern as in FIG. 3b, a substantial lengthening of the linear zone isachievable, here a quintuple lengthening, from about 100 Hz to about 500Hz.

[0046] Obviously the deflection of the particle jet from the outletopening 9 does not necessarily have to be effected by a movement of thisoutlet opening. Thus, it is also conceived that the particles aredeflected by the forces acting on them directly during their movement,and the particle jet is constructed in this manner. Thus, for example,as a deflecting device there can be provided arrangements for thegeneration of a variable electric or magnetic or electromagnetic fieldbetween the outlet opening 9 and the vibration sensor 2.

[0047] Advantageously as represented in FIGS. 7 to 9, similar to anoscilloscope, two pairs of cooperating electrodes 10 are provided which,for the achievement of their optimal action on the particles 1, arearranged between the outlet opening 9 and the vibration sensor 2, to theside of the path of the particle jet. By a corresponding drive of thetwo electrode pairs, preferably alike over the electronic switchingarrangement 4, variable electric fields can be generated, by which theparticle jet can be deflected in an arbitrary direction and aboutarbitrary angles, and in this manner can be led over the activecollecting surface 5 of the vibration sensor 2. Preferably closed pathsare generated by this arrangement, for example circular paths or pathswhich arise from the superposing of two circular movements.

[0048] In the case of the electrostatic precipitation of the particles 1on the active collecting surface 5 of the vibration sensor 2, there mustbe provided for its ionization a corona needle. By a movement of thiscorona needle or other structure over corresponding arrangements, ifnecessary over a movable bearing of the corona needle, fieldcharacteristic of the needle can be changed, which again leads to aninfluence of the alignment and form of the particle jet passing thecorona needle and emerging from the outlet opening. Here a movement ofthe corona needle is conceivable which is not only essentially parallelto the active collecting surface 5, but also essentially perpendicularto this collecting surface 5, or a movement that arises from asuperposing of the earlier mentioned movements. This variant can be usedalone or in combination with the earlier-described variation of anelectrical, magnetic, or electromagnetic field for the deflection of theparticle jet.

[0049] In FIG. 8 there is schematically represented a form of executionin which the deflection of the particle jet is achieved over thecollecting surface 5 by means of an arrangement of two crossed pairs ofmagnets 11. An embodiment with a combination of electrical and magneticdeflection is represented in FIG. 9 and it can be especiallyadvantageously used where smaller space requirement for the arrangementis necessary. Here, namely, only two arrangements lying opposite oneanother are necessary for the deflection of the particles over thecollecting surface, which are constructed in each case from an electrodeplate 13 with a magnetic winding 12 mounted on it or directly behind it.By use of different voltages on the electrode plates 13 there can bebrought about a deflection in its connection direction, while themagnetic winding 12 generates a magnetic field likewise in a connectiondirection, which, however, brings about the desired deflection of theparticles perpendicular thereto.

[0050] Finally, let there also be mentioned a further embodiment of theinvention, in which the deflection of the particle jet is achieved bythe means that a jet of a neutral pure gas is led laterally onto theparticle jet, and deflects the particle jet therefore with respect tothe uninfluenced beam direction. Obviously the amount of the pure gasmust be taken into consideration in the determination of concentration,which can be ensured, for example, by means of flow sensors and theirinterrogation by the evaluating circuit arrangement 4. There, the puregas is injected into the measuring chamber, preferably over at least onefurther outlet opening, the axis of which encloses an angle not equal tozero with the axis of the outlet opening 9 for the particle jet. Ifnecessary, the outlet opening for the pure gas is adjustable in itsdirection and/or the flow speed of this pure gas is variable, in orderto make possible a different influence of the particle jet.Alternatively or in addition to this, it would be possible bycooperation of two or more pure gas outlet openings, if necessary withineach case alternating flow velocity, to achieve a deflection of theparticle jet in more complex patterns, which allow a guidance of theparticle jet over the active collecting surface 5 of the vibrationsensor 2 also, for example, in closed paths, preferably circular pathsor paths arising by superposition of several circular movements.

[0051] As is apparent from the foregoing specification, the invention issusceptible of being embodied with various alterations and modificationswhich may differ particularly from those that have been described in thepreceding specification and description. It should be understood that wewish to embody within the scope of the patent warranted hereon all suchmodifications as reasonably and properly come within the scope of ourcontribution to the art.

We claim as our invention:
 1. An arrangement for the quantitative andqualitative analysis of particles in a an gas, comprising: a measurechamber with at least one entry opening for the gas to be analyzed, avibrating system having at least one vibration sensor held essentiallystationary relative to the measuring chamber, at least one collectingsurface for the particles to be analyzed associated with the vibrationsensor, an electrical circuit for the determination of characteristicvibration parameters of the vibrating system, guide and transportarrangements for the gas to be analyzed, and at least one active deviceto at least one of guide and steer at least one of the gas and theparticles contained in the gas.
 2. An arrangement according to claim 1,wherein the particles are particles in the exhaust gas of an internalcombustion engine.
 3. An arrangement according to claim 1, wherein thecollecting surface comprises a piezoelectric resonator.
 4. Anarrangement according to claim 1, wherein the active device comprises ashutter with at least one shutter opening, the traversable cross sectionarea of which is small as compared to a collecting surface of thevibration sensor, in combination with an arrangement for a movement ofthe shutter relative to and essentially parallel to the collectingsurface of the vibration sensor.
 5. An arrangement according to claim 4,wherein an arrangement is provided for moving the shutter, whicharrangement moves at least one shutter opening in a closed path.
 6. Anarrangement according to claim 4, wherein an arrangement is provided formoving the shutter, which arrangement moves at least one shutter openingin an essentially circular path, in which an axis of the circular pathis oriented essentially perpendicular to the collecting surface of thevibration sensor.
 7. An arrangement according to claim 6, wherein atleast one of the vibration sensor and its collecting surface isconstructed rotationally symmetrical about the axis of the circularpath.
 8. An arrangement according to claim 4, wherein an arrangement isprovided for moving the shutter, which arrangement moves at least oneshutter opening on a path that arises by a superposing of at least tworotary movements with essentially parallel axes of rotation, which axesof rotation are oriented essentially perpendicular to the collectingsurface of the vibration sensor.
 9. An arrangement according to claim 1,wherein an arrangement is provided for moving the shutter relative tothe vibration sensor with alternating speed.
 10. An arrangementaccording to claim 1, wherein an arrangement is provided for moving theshutter relative to the vibration sensor with alternating angularvelocity.
 11. An arrangement according to claim 1, wherein the activedevice comprises a corona needle which is coupled together with anarrangement for its movement relative to the vibration sensor.
 12. Anarrangement according to claim 1, wherein the active device comprises atleast one arrangement for the generating at least one of a variableelectric, magnetic or electromagnetic field between the outlet openingand the vibration sensor, and an arrangement for the electrical chargeof the particles in the gas.
 13. An arrangement according to claim 1,wherein the active device comprises at least one outlet opening for anadditional gas jet, axes of the two outlet openings preferably enclosingwith one another an angle not equal to zero.
 14. An arrangementaccording to claim 13, wherein the outlet opening for an additional gasjet is located to the side of the opening for the entry of the particlesinto the measuring chamber.
 15. An arrangement according to claim 1,wherein the active device is designed for the generation of at least oneof an alternating flow speed and direction of the jet of the gas to beanalyzed.
 16. An arrangement according to claim 15, wherein the activedevice is designed for the generation of at least one of alternating gasor particle velocities in the entry opening.
 17. A process for thequantitative and qualitative analysis of particles in a gas, comprisingthe steps of precipitating particles in a jet through at least oneoutlet opening onto at least one collecting surface of at least oneessentially stationary vibration sensor of a vibrating system,determining a change in characteristic vibration parameters on a basisof the particle precipitation, and actively moving the particle jet overan ever alternating zone of the collecting surface of the vibrationsensor.
 18. A process according to claim 17, wherein said gas comprisesan exhaust gas of an internal combustion engine.
 19. A process accordingto claim 17, wherein said vibration sensor comprises a piezoelectricresonator.
 20. A process according to claim 17, including the step ofguiding the particle jet along a closed curve.
 21. A process accordingto claim 17, including the step of guiding the particle jet along acircular path.
 22. A process according to claim 17, including the stepof guiding the particle jet which arises by superposition of at leasttwo rotary movements with axes of rotation perpendicular to the activecollecting surface.
 23. A process according to claim 17, including thestep of guiding the particle jet with alternating speed.
 24. A processaccording to claim 17, including the step of guiding the particle jetwith alternating angular velocity.
 25. A process according to claim 17,including the steps utilizing an electric field to ionize the particlesand deflecting and guiding the particle jet by at least one ofalternating electrical magnetic and electromagnetic fields.
 26. Aprocess a claim 25, including the step of continuously varying theelectric field used for the ionization of the.
 27. A process accordingto claim 17, including the step of deflecting the particle jet bydirecting a gas jet of at least one of alternating flow speed anddirection onto the particle jet.
 28. A process according to claim 17,including the step of aiming the gas jet containing the particles withat least one of an alternating flow speed and flow direction onto thecollecting surface of the vibration sensor.
 29. A process according toclaim 17, including the step of directing the particles through theentry opening into the measuring chamber with alternating speed.